A police officer accused of using excessive force in arresting a G20 protester testified at his own trial on Monday, emphasizing that he did as he was trained when he struck and jabbed a protester with his police baton in an effort to control him.

Const. Babak Andalib-Goortani has pleaded not guilty to assaulting G20 protester Adam Nobody with a weapon.

His testimony on Monday caused him to break down in tears at one point, and the court had to take a break so he could compose himself enough to speak. The day he was recalling, he said, was the hardest day of his policing career.

Throughout his testimony, the officer maintained that Nobody was resisting arrest when he struck and jabbed him. But in cross-examination, prosecutor Philip Perlmutter suggested the officer may have misinterpreted Nobody’s actions.

The officer’s work day started at 7 a.m. on Saturday, June 26, 2010, and Andalib-Goortani was supposed to work a 12-hour shift. His team, called mobile team five, was supposed to control traffic during protests. Throughout the day, he says he was told not to engage protesters, but rather to run away from them.

His shift ended up lasting 17 hours, and his role at the end of the day, he testified, was much different than the one he was first assigned.

Just before 1 p.m. that day, the crowd swelled. He estimated thousands of people congregated near Queen’s Park. Someone in the crowd lit a flare, and memory of seeing the smoke billow above brought the officer to tears on the witness stand.

Not long after, he heard the voice of another officer on his radio. He said the officer yelled that he was being attacked, that he was outnumbered and needed help. Protesters were coming from every direction, the cop testified, and some were picking up bricks or sticks to use as weapons.

“There was nothing I could do,” Andalib-Goortani said about the officer on the radio.

He saw mostly peaceful protesting when he moved to College and Spadina, but the chatter on his police radio increased.

He regrouped near Bloor St. and Avenue Rd., where he was told to put his gas mask and helmet on. A one-day training course before the summit had taught him how to use the equipment, he said.

When he returned to Queen’s Park, what remained of his team — some were split away in the confusion — lined up behind officers from the public order unit.

A staff sergeant gave him a direct order. Andalib-Goortani’s team was to become an arrest unit, something the officer says he hadn’t been trained to do during the summit.

Their job, he testified, was to dart out from behind the public order officers and arrest the people the public order officers pointed out.

Adam Nobody was one of those people. Andalib-Goortani says he didn’t know him at the time, but the officer testified that he would stand out as the most resistant protester that day.

“I heard, ‘There he is! Get him! Get him,’ ” the officer said in reference to Nobody.

An officer rushed over and tackled Nobody. The officer’s legs were in the air, Andalib-Goortani said, and Nobody was in between them.

Andalib-Goortani believed Nobody was resisting arrest and trying to get away, but Perlmutter suggested he may have just been trying to get untangled from the officer.

Andalib-Goortani says he was trained to use force as a distraction. While standing over Nobody, he says he struck him with his baton, aiming for the muscle mass in his thigh.

He says he then walked over toward Nobody’s head, trying to block officers from being hit by other people in he crowd.

The officer says Nobody continued to resist, and on several occasions, he heard his colleagues yell, “stop resisting!”

He says he thought Nobody was trying to get up and get away.

While kneeling down, he testified that he jabbed him once in the thigh with his baton, paused for a few seconds, then jabbed him twice more. He “consciously aimed” for the thigh, though the Crown suggests he may have missed his target, hitting Nobody higher up on his waist.

“That’s what I was striking for and that’s what I hit, sir,” Andalib-Goortani said, referring to Nobody’s thigh.

Later, he admitted he may have hit higher because Nobody was moving, but to the best of his recollection, he said, he hit where his target.

At the end of his cross-examination of the cop, Perlmutter suggested Andalib-Goortani was put in a situation he wasn’t trained for. The situation was frightening, tense and chaotic, and the prosecutor suggested the officer was angry at the protesters.

“You broke. You snapped and you lashed out in anger and frustration,” Perlmutter said.

The officer admitted it was the hardest day of his career. And though he disliked what the protesters were doing, he said, he still had a job to do. He felt as if he needed to do something to help officers get Nobody under control, and said he felt he was helping finish the arrest.

“I was doing the best I could.”

The trial continues Tuesday, with the defense expected to call more witnesses